'99, 5.2, 100,000 miles. I've had this problem since buying it used 3 years ago at 73,000 miles. It has always been an annoyance, but I didn't want to take the time to troubleshoot it.

Idles fine and accelerates strong. The problem occurs at steady speeds from 35mph and up, like when using cruise control. The hesitations (split second dropouts) produce a jerky sensation, as if the motor has irregular hiccups. It isn't steady, like a bad plug. It doesn't affect speed.

And if I accelerate, it goes away completely and the motor is smooth under acceleration. Injector?

A mechanic suggested the fuel filter. But if the filter were clogged wouldn't the problem be worse under acceleration, as the fuel delivery would be even more restricted? Seems like it to me.

I have seen temporary/brief improvement after running a couple tanks of Seafoam through, but then it's back. This suggests the injectors. How should I test them or clean them thoroughly?

Any help much appreciated. Thanks.........

 

If it happens often enough..... Watch what the tach does when the problem presents itself. If it 'bounces' about 200 RPM, might be as simple as a bad TPS.

Not sure if there is an effective method of cleaning your injectors at home.....

 

I will watch the tach. Meanwhile, can most shops clean the injectors, and what is a ballpark price for the service?

 

Would have to call around, and ask. Not something everyone does, and some folks are better at it than others...... and rates vary as much as wind speed.

 

Turns out there is no change in rpms or speedo, so I'll pursue the injector idea. It sure acts like what a poorly functioning injector would do, ie: wide open on acceleration is fine, but holding a smooth mid-range isn't.

 

How many miles on the truck, and are your O2 sensors original?

 

100,000. I bought it at 73,000 and haven't changed them. They are probably original.

 

Try unplugging the front one, and see if the problem goes away.

 

Mine gets a little jittery like that every time the heat from my headers messes up the #6 and/or #8 spark plug wires.